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(1 - 4 of 4)
- Title
- SELENOTRISULFIDE DERIVATIVE OF ALPHA-LIPOIC ACID: EVALUATION IN A CELL CULTURE MODEL FOR POTENTIAL USE AS A TOPICAL ANTIOXIDANT.
- Creator
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Alonis, Melenie, Self, William, University of Central Florida
- Abstract / Description
-
Selenium is a required micronutrient in mammalian cells. It is incorporated in the form of selenocysteine into selenoenzymes such as glutathione peroxidase and thioredoxin reductase, and is absolutely required for activity. Thioredoxin reductase is necessary for reduction of oxidized thioredoxin and therefore plays a major role in maintaining the redox status of the cell. Glutathione peroxidase is responsible for reducing peroxides into their corresponding alcohols and water. Together, these...
Show moreSelenium is a required micronutrient in mammalian cells. It is incorporated in the form of selenocysteine into selenoenzymes such as glutathione peroxidase and thioredoxin reductase, and is absolutely required for activity. Thioredoxin reductase is necessary for reduction of oxidized thioredoxin and therefore plays a major role in maintaining the redox status of the cell. Glutathione peroxidase is responsible for reducing peroxides into their corresponding alcohols and water. Together, these selenoenzymes constitute a significant part of the cell's arsenal to defend itself against oxidative stress. Exogenous sources of oxidative stress, such as UV radiation, are capable of generating reactive oxygen species (ROS). Elevated levels of ROS can lead to covalent modifications of lipids, nucleic acids, and proteins within a cell. This damage has been implicated in the development of cancer and degenerative diseases. As the skin is the first level of defense for UV radiation, skin cancer is an obvious concern. Previous studies have demonstrated a protective effect against UV-induced cytotoxicity when selenium compounds were administered to skin cells in cell culture models. Topical selenium application to mice has also been shown to reduce UV damage to skin. Although a variety of chemical forms of selenium are available in nutritional supplements, the efficiency by which they are used for selenoprotein synthesis varies greatly. It is debated within the selenium research community which form is best for use as a supplement. In this study, we have focused on a selenotrisulfide derivative of alpha-lipoic acid (LASe). We have examined its utilization for selenoprotein synthesis through radiolabeling studies (75Se) in a human keratinocyte cell line (HaCaT). We have determined that is incorporated into selenoproteins with nearly the same efficiency as selenite and L-selenocysteine. We have also determined that LASe is far more efficient as a supplement in cell culture than selenate or L-selenomethionine, two forms of selenium commonly used as supplements. LASe was also found to protect HaCaT keratinocytes from UV- induced cytotoxicity. Cells pretreated with LASe and exposed to 500J/m2 and 750J/m2 of broadband (UVA/UVB) UV radiation showed greater survival than untreated controls in a dose –dependent manner. Cells pre-treated either with lipoic acid or selenium in the form of selenite alone also observed protection. Nonetheless, these finding are significant given that LASe was previously shown to penetrate the skin better than other forms of selenium. These results indicate that LASe has the potential for use as a topical antioxidant upon further testing in animal studies.
Show less - Date Issued
- 2005
- Identifier
- CFE0000663, ucf:46531
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000663
- Title
- Expression of Trichoderma reesei (&)#223;-Mannanase in Tobacco Chloroplasts and its Utilization in Lignocellulosic Woody Biomass Hydrolysis.
- Creator
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Agrawal, Pankaj, Daniell, Henry, Kolattukudy, Pappachan, Self, William, University of Central Florida
- Abstract / Description
-
Lignocellulosic ethanol offers a promising alternative to conventional fossil fuels. One among the major limitations in the lignocellulosic biomass hydrolysis is unavailability of efficient and environmentally biomass degrading technologies. Plant-based production of these enzymes on large scale offers a cost effective solution. Cellulases, hemicellulases including mannanases and other accessory enzymes are required for conversion of lignocellulosic biomass into fermentable sugars. ?...
Show moreLignocellulosic ethanol offers a promising alternative to conventional fossil fuels. One among the major limitations in the lignocellulosic biomass hydrolysis is unavailability of efficient and environmentally biomass degrading technologies. Plant-based production of these enzymes on large scale offers a cost effective solution. Cellulases, hemicellulases including mannanases and other accessory enzymes are required for conversion of lignocellulosic biomass into fermentable sugars. ?-mannanase catalyzes endo-hydrolysis of the mannan backbone, a major constituent of woody biomass. In this study, man1 gene encoding ?-mannanase was isolated from Trichoderma reesei and expressed via the chloroplast genome. PCR and Southern hybridization analysis confirmed the site-specific transgene integration into the tobacco chloroplast genomes and homoplasmy. Transplastomic plants were fertile and set viable seeds. Germination of seeds showed inheritance of transgenes into the progeny without Mendelian segregation. Expression of the endo-?-mannanase gene for the first time in plants facilitated its characterization for use in enhanced lignocellulosic biomass hydrolysis. Gel diffusion assay for endo-?-mannanase showed the zone of clearance confirming functionality of chloroplast-derived mannanase. Endo-?-mannanase expression levels reached up to 25 units per gram of leaf (fresh weight). Chloroplast-derived mannanase had higher temperature stability (40 (&)deg;C to 70 (&)deg;C) and wider pH optima (pH 3.0 to 7.0) than E.coli enzyme extracts. Plant crude extracts showed 6-7 fold higher enzyme activity than E.coli extracts due to the formation of disulfide bonds in chloroplasts, thereby facilitating their direct utilization in enzyme cocktails without any purification. Chloroplast-derived mannanase when added to the enzyme cocktail containing a combination of different enzymes yielded 20% more glucose equivalents from pinewood than the cocktail without mannanase. Our results demonstrate that chloroplast-derived mannanase is an important component of enzymatic cocktail for woody biomass hydrolysis and should provide a cost-effective solution for its diverse applications in the paper, oil, pharmaceutical, coffee and detergent industries.
Show less - Date Issued
- 2011
- Identifier
- CFE0004467, ucf:49309
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004467
- Title
- Fabrication and Investigation of an enzyme-free, Nanoparticle-based Biosensor for Hydrogen Peroxide determination.
- Creator
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Neal, Craig, Seal, Sudipta, Cho, Hyoung Jin, Florczyk, Stephen, University of Central Florida
- Abstract / Description
-
Electrochemical biosensors often employ enzymes as detection elements. These sensors are highly selective towards target analytes, however the scope of their application is limited by the poor stability of the enzyme. In this study, multi-valent inorganic cerium oxide nanoparticles were used as detection elements for the analysis of hydrogen peroxide. The electrochemical response of the cerium oxide towards hydrogen peroxide analyte is defined through cyclic voltammetry and chronoamperometry....
Show moreElectrochemical biosensors often employ enzymes as detection elements. These sensors are highly selective towards target analytes, however the scope of their application is limited by the poor stability of the enzyme. In this study, multi-valent inorganic cerium oxide nanoparticles were used as detection elements for the analysis of hydrogen peroxide. The electrochemical response of the cerium oxide towards hydrogen peroxide analyte is defined through cyclic voltammetry and chronoamperometry. This response was found to be dependent on nanoparticle Ce3+:Ce4+ redox state ratio and this property is exploited to fabricate a biosensor. As produced, the biosensor demonstrated sensitivity at picomolar analyte concentrations. Further, the sensitivity of the electrode is stable across a range of temperatures and pH's which inhibit the function of standard enzyme-based sensors. Additionally, the produced sensor retained function in sheep serum demonstrating the high selectivity and robustness of the sensor.
Show less - Date Issued
- 2016
- Identifier
- CFE0006362, ucf:51540
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006362
- Title
- A Preliminary Assessment of Steroid Reproductive Hormones in Archaeological Human Hair Utilizing a Modified Enzyme-Linked Immunosorbent Assay (ELISA) Technique.
- Creator
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Tisdale, Elisha, Schultz, John, Williams, Lana, Wheeler, Sandra, University of Central Florida
- Abstract / Description
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Hair has become an invaluable resource in forensic, clinical, and bioarchaeological research. The unique interaction between the growing hair fiber, the hair follicle, and the endocrine system inundates the growing hair fiber with an incremental record of many of the discreet physiological processes of the body. Recently, a novel study by Webb et al. (2010) demonstrated that endogenous records of cortisol, the (")stress hormone("), are capable of being extracted from archaeological human hair...
Show moreHair has become an invaluable resource in forensic, clinical, and bioarchaeological research. The unique interaction between the growing hair fiber, the hair follicle, and the endocrine system inundates the growing hair fiber with an incremental record of many of the discreet physiological processes of the body. Recently, a novel study by Webb et al. (2010) demonstrated that endogenous records of cortisol, the (")stress hormone("), are capable of being extracted from archaeological human hair through a modified enzyme-linked immunosorbent assay (ELISA) technique, thus providing insight into the (")invisible(") stress experiences of an individual that would otherwise not be detectable through skeletal analysis. The present study seeks to apply this novel ELISA technique to archaeological hair to determine whether endogenous patterns of secretion are detectable for the steroid reproductive hormones estradiol and testosterone. Here, hair from 10 individuals from the Kellis 2 cemetery in the Dakhleh Oasis, Egypt is analyzed for endogenous concentrations of the steroid hormones cortisol, estradiol, and testosterone. A control sample consisting of hair from 10 modern cadavers is also assessed for each hormone to ensure method efficacy. Cortisol, estradiol, and testosterone were successfully identified in all 10 archaeological individuals and in each of the 10 individuals in the modern control group. Results revealed that archaeological preservation of each hormone was favorable, and incremental patterning of each hormone seem to reflect endogenous hormone secretion in life. Values for cortisol, estradiol in pre-menopausal females, and testosterone extracted from the archaeological and modern control samples fall within reference values taken from archaeological and clinical research; however, estradiol values for males and postmenopausal females exceeded projected reference values. Explorations for variables which could contribute to discrepancies between reported and observed estradiol values are provided, along with two case studies on female individuals from the archaeological sample. The results of this study demonstrate that steroid reproductive hormones can be preserved in archaeological human hair, and that these hormones can be analyzed to create additional lines of inquiry into bioarcheological studies of ancient health and fertility.
Show less - Date Issued
- 2017
- Identifier
- CFE0006921, ucf:51700
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006921
